Anti-algae efficacy of silver nanoparticles to Microcystis aeruginosa: Influence of NOM, divalent cations, and pH

The effects of water components (nature organic matters and inorganic cations) and pH on the anti-algae efficacy of silver nanoparticles (AgNPs) against Microcystis aeruginosa were studied. Humic acid decreased the antimicrobial toxicity of AgNPs on M. aeruginosa while calcium and magnesium ions enhanced toxicity. The anti-algae efficacy was greater at low pH. The physicochemical properties of AgNPs were studied to determine the role of nanomaterial contact with M. aeruginosa and the effect of silver ions on algaecidal toxicity. A comparison of particle sizes and silver ion changes under different water conditions showed that direct contact of nanoparticles with algae cells and the release of silver ions both contributed to anti-algae ability. The dominating mode of action of the AgNPs may occur through direct contact of AgNPs particles with algae cells rather than through toxicity effects from the silver ion. (C) 2016 Elsevier B.V. All rights reserved.